Digitalization has profoundly reshaped work modes and lifestyles and impacted individuals' life satisfaction. However, there has been limited research exploring this issue while comparing the effects before and during the COVID-19 pandemic. Furthermore, investigating heterogeneity across different socio-economic groups is crucial. This study uses data from the latest three waves of the European Social Survey in 2016, 2018, and 2020 to examine the influence of Internet usage on life satisfaction, unravel its underlying mechanisms, and conduct heterogeneity analysis with the fixed-effects ordered logit model and propensity score matching method. The empirical findings reveal the following: (a) Internet usage has significant and positive effects on life satisfaction, although the marginal effects of Internet usage decreases as respondents’ life satisfaction increases; (b) respondents with a “right” political tendency, higher levels of social interaction and trust, females, older individuals, higher income earners, those with lower education levels, better health conditions, and stronger religious beliefs tend to report higher life satisfaction; (c) work flexibility, work–life balance, and team engagement are identified as essential mediating factors in the relationship between Internet usage and life satisfaction; (d) Internet usage has had a significant and positive effect on life satisfaction since the outbreak of the COVID-19 pandemic, whereas this was not the case before the pandemic; and (e) the influence of Internet usage on life satisfaction is more pronounced among young, affluent communities, well-educated individuals, Eastern and Central Europeans, non-managers, and employees of central/local governments and private firms. This study underscores the rapid socio-economic transformation induced by digitalization in Europe and provides valuable insights on leveraging the Internet to improve individual life satisfaction in the post-pandemic era.